1. Field of the Invention
The present invention relates to an endoscope having, at a distal end portion of an insertion section, a raising base for switching the direction of a treatment instrument which is guided outside from a distal end opening provided in the insertion section and a rigid distal end portion of an endoscope.
2. Description of the Related Art
As a medical endoscope, there is a so-called duodenoscope, which is a side-view type endoscope (hereinafter referred to as an endoscope) having an illumination lens and an objective lens arranged on a side surface on the distal end side of an insertion section.
The endoscope is used for surgical techniques such as endoscopic retrograde cholangiopancreatography for imaging a pancreaticobiliary duct through a duodenum, or endoscopic papillotomy for removing a choledocholith (bile duct stone).
The endoscope is provided with a treatment instrument insertion channel and a raising device.
The treatment instrument insertion channel is a tubular body with a through hole for inserting a treatment instrument such as a contrast tube, a basket catheter, or a balloon catheter. The treatment instrument insertion channel is disposed inside an insertion section, along a longitudinal axis of the insertion section. A distal end of the treatment instrument insertion channel is connected to a distal end portion main body forming a distal end portion of the endoscope, and its proximal end is connected to a treatment instrument insertion opening provided in an operation section.
On the other hand, the raising device is a device for switching, to a desired direction, the direction of a treatment tool which is passed through the treatment instrument insertion channel and is guided to outside from a distal end opening provided in the distal end portion main body. Generally, the raising device is configured mainly from a raising base which is rotatably disposed to the distal end portion main body, a raising base operation lever provided in the operation section, and a raising base operation wire configured to move according to operation of the raising base operation lever and to swing the raising base.
Japanese Patent Application Laid-Open Publication No. 8-56900 discloses an endoscope which allows even a treatment instrument or the like with a narrow distal end to smoothly protrude without getting caught in a raising base operation wire, and to be easily guided by being observed near the center of an observation field of view.
According to the endoscope, an observation window is provided in one of left and right half portions on side surfaces of a distal end of an insertion section, and a treatment instrument raising base to be swung in the front-back direction by remote operation is provided in the other half portion. A pair of inner and outer walls which are in contact with both side surfaces of the treatment instrument raising base in the swinging range of the treatment instrument raising base are formed to the distal end of the insertion section, and a distal end of an operation wire to be remotely operated is disposed on a back side of the outer wall surface, and motion of a distal end of the operation wire is transmitted to the treatment instrument raising base by a driving force transmission member disposed penetrating the outer wall.
That is, as shown in FIG. 1 of Japanese Patent Application Laid-Open Publication No. 8-56900, at a distal end portion main body forming a distal end portion of the insertion section of the endoscope, the observation window and an illumination window are arranged in the longitudinal axis direction of the distal end portion main body, the treatment instrument raising base is rotatably provided between an inner wall and an outer wall facing each other across the longitudinal axis, a raising base drive lever is provided in a raising base drive chamber formed in a recessed manner on an outer side surface of the outer wall, on the other side of the longitudinal axis, and an operation wire is fixedly installed to the raising base drive lever by a pin.
Moreover, an opening portion of the raising base drive chamber is blocked in a liquid-tight manner by a sealing lid, and an insulating plastic cover is externally attached to the distal end portion main body. Furthermore, a liquid, such as a body fluid, is prevented from entering into a raising base accommodating chamber from outside by providing an O-shaped ring to the raising base drive lever.
Also, the observation window and the illumination window are provided in a liquid-tight manner to the distal end portion main body. As a result, a liquid is prevented from entering from outside into the distal end portion main body through the observation window and the illumination window.